Endoscopic surgical instruments for removing tissue or bone are known. Such instruments generally comprise a hollow tubular proximal member, a hollow distal end member having a window therein, a cutting device which is housed in the distal end member and part of which protrudes beyond the window in the distal member, and a shaft which passes through the proximal member and operates the cutting device. The term “cutting device” is used in this specification to include any device which can be used to cut or debride bone or tissue, including but not limited to blades, burs and microdebriders. The term “endoscopic” is used in this specification to include, but is not limited to, procedures such as arthroscopy, laparoscopy, subdermal percutaneous surgery, ENT, trauma, subacromial decompression, acromioplasty, notchplasty for ligament repair, osteochondral debridement for osteochondral defect, ACL, OCD repair in the knee, and other minimally invasive surgical procedures. For information about known endoscopic surgical instruments, reference may be made, for example to U.S. Pat. Nos. 4,646,738, 5,250,059, 5,254,130, 5,411,514, 5,669,926, 5,833,692, 6,290,709, and 7,951,161, US Patent Publications 2008/0125759, 2011/0071356 and 2010/0087711 The entire disclosure of each of those patents and publications is incorporated herein by reference for all purposes.